d . M.G.
4-00 jj 64-5
63-5 ! 3-75
For each 0-1° variation in M.G. the difference d changes by 0-05°, and
the sum M.G. + id, is never less than 71 with pure hog's fat. Hog's fat
containing tallow of whatever origin or pressed tallow or hardened oil
gives a lower value of d than is shown in the above table, while M.G. + zd
is less than 71.
EXAMPLES : A hog's fat gave : M.G. = 63-5° and M.A. ='58°, so that
d = 5-5 and M-G. + 2d = 74-5° ; the fat is thus pure.
Another fat gave : M.G. =63° and M.A. = 60-5°, so that rf = 2-5° and
M.G. + 2d = 68. This fat contains tallow (pressed tallow, hardened oil).
3. VEGETABLE OILS AND FATS. COTTONSEED STEARINE. These adul-
terants are detected as follows :
(a) Colour reactions. Bellier's reaction (see General Methods, 23, 4)
shows the presence of seed oils in general; Villavecchia and Fabris' reaction
that of sesame oil (q.v.} ; Halphen's reaction and the silver nitrate reaction
according to Armani or Tortelli and Ruggeri, that of cottonseed stearine
(see Cottonseed Oil).
Arachis oil is detected by the reaction for arachidic and lignoceric acids
(see Arachis Oil).
(b) Various characters. Determinations are also made of the saponifi-
cation, volatile acid and Polenske numbers (see General Methods, 8 and
10 of this chapter, and Butter, Vol. II), which detect the presence of coco-
nut oil; of the ordinary and absolute iodine numbers (see General Methods,
12 and 13), which serve to confirm the presence of seed oils and to give an
approximate indication of their quantity (when the nature of the vegetable
011 has been ascertained) ; and of the rotatory power, for the detection of
Hydnocarpus (Maratti) and Mowrah fats (see later, d).
As subsidiary determinations, measurements may also be made of the
Zeiss refractometric reading at 40° (see Butter) and of the Maumene number
(see General Methods, 21).
(c) Detection of phytosterol. This is of special importance in the analysis
of lard, since only with its help can it be decided if vegetable oils have really
Like all other animal fats and oils, hog's fat contains, as unsaponifiable
substance, cholesterol (about 0-2% in the crude state), whereas the un-
saponifiable substance of vegetable oils and fats consists of phytosterol.
The crystalline form and. the melting point of the unsaponifiable substances
suitably purified (see General Methods, 19) and, better still, the melting
point of their acetyl compounds serve to detect mixtures of cholesterol
For the detection of phytosterol in lard (and, in general, in other animal as the melting p.oint. The deter-